Maria Shriver often told the story of first meeting Arnold Schwarzenegger in 1977, when he laid on the charm by informing her, in front of her mother, "You have a great a--."

She decided at that moment, "This man I want to get to know."

The couple's separation announcement on Monday came as a surprise to many, especially given that they'd celebrated their 25th anniversary together on April 26 and spent Mother's Day with their four kids, Katherine, 21, Christina, 19, Patrick, 17, and Christopher, 13.

"We both love each other very much," Schwarzenegger shared Tuesday night, as he accepted an award during the 63rd Israel Independence Day Celebration at the Skirball Cultural Center in Los Angeles. "We're very fortunate to have four extraordinary children. And we're taking it one day at a time."

So, what went wrong?

"Everyone who's shocked by this is reacting to the fairy-tale picture that was promoted," a source tells the Los Angeles Times. "There was such a void, and when she looked around, she realized her husband could never even think of filling it."

Insiders say that Shriver has felt "trapped for years in an unhappy relationship," which apparently reached a "breaking point" following the deaths of her parents, Eunice Kennedy Shriver (in 2009) and Sargent Shriver (in January), and her transition away from public life following Schwarzenegger's term as governor of California.

According to a source, she stuck it out for a number of reasons: "Part of it is family legacy, part of it is Catholicism. But the most important thing was their four kids."

But a "miserable" Maria, 55, supposedly grew tired of Ahnuld, 63, "ignoring her and her needs," alleges TMZ, which says that the former muscle-bound box office champ is now "working extremely hard" to win back his estranged missus by "changing his ways."

"Arnold has done a 180," maintains a spy. "He could not be sweeter now that she's left him."

His purported change in attitude has left Shriver feeling "ambivalent" about the breakup, maintains a source, with another adding, "Maria has been tortured over pulling the plug on the marriage. One day she's determined to get the hell out, and the next day she just can't do it."

TMZ claims Shriver had been considering dropkicking her famous spouse for a couple of years, citing how "impossible" he is to live with and her weariness with the longtime rumors of his wandering eye, which were extensively detailed in an infamous 2001 article in Premiere magazine.

Their kids, seemingly aware of their parents' issues, are said to have supported Shriver's decision to move out of the family's Brentwood estate.

On Tuesday, Patrick tweeted, "Appreciate all your messages. Small speed bump in life, luckily we own hummers, we will cruise right over it. All will be okay. #peace."

Arnold also expressed his gratitude for the support he and Maria have received.

"We both were saying the same thing: We are amazed and extremely blessed to be surrounded by so many wonderful people, by so many wonderful friends," he said Tuesday. "The bottom line is, we want to thank all the people for their great, great support."